1. Field of the Invention
This invention relates to a liquid chromatograph analysis apparatus and a liquid chromatograph analysis method.
2. Description of the Related Art
In the liquid chromatograph analysis apparatus, when an analysis is started or when a solvent is replaced, it is necessary to execute a purge operation for replacing liquid in a tube or removing air bubbles entered in the tube. In a related art, in doing such a purge operation, a user performing an analysis needs to manually operate a switching valve for switching between a main flow path for analysis and a discharge flow path for purging. Such a manual purge operation is troublesome for the user, and is a great obstacle to achieve a complete automated analysis by the liquid chromatograph.
However, in doing the purge operation, it is necessary to feed the liquid at a flow rate approximately equal to or greater than that in the main flow path. Therefore, in a case where the apparatus automatically switches the switching valve for switching between the main flow path for analysis and the discharge flow path for purging, a flow path pressure may reach a pressure upper limit value so that a system stops during the purging. In order to obviate such an inconvenience, a system using a dedicated hardware for managing a flow path length and a tube diameter is developed (for example, refer to JP-A-2001-255316).
However, in the case of the system using the dedicated hardware as described above, there is a problem that a flow path configuration is limited so as to simplify a control. In addition, it is difficult to realize the automated purging in a desired flow path configuration according to an analysis purpose. Further, in the system using the dedicated hardware, the flow path that can be automatically purged and the flow path that cannot be automatically purged are both provided.
Further, usually, in the liquid chromatograph analysis apparatus, an analysis file in which sample numbers, an analysis order, an analysis condition for each sample, and the like are defined is previously created by an user. By controlling respective sections of the apparatus according to the analysis file, the analysis is executed according to a desired procedure and condition. Therefore, even in the liquid chromatograph which is not equipped with the above dedicated hardware, by using such a function, it is possible to create the analysis file including operation commands for purging at a start and an end of a sequential sample analysis. The purge operation can be performed by executing the analysis file. However, since the purge operation in this case is performed as a part of analysis, at the utmost, the user cannot invoke a command for purging as required to execute the command instantaneously. Further, since measurement data is generated also while the purge operation is performed, a time and labor of deleting unnecessary measurement data are taken, and a problem may occur such that deleting of the data is forgotten.
Further, in an analysis using a buffer solution in which an ionic compound is dissolved as the solvent, frequently, a gradient system in which two or three types of liquids are used is employed, and one or two types of liquids are employed as cleaning fluid. In such a case, when the system remains in a state that the buffer solution is left in the flow path, for a long time, the ionic compound may be precipitated to block the flow path or the precipitated crystal may damage a seal or the like of a driving system. Further, the tube may be corroded. In order to obviate such an inconvenience, usually, where the analysis is not performed after the buffer solution is used, the buffer solution is replaced into a nonionic liquid so as to be stored. In this case, when a solubility of the ionic compound with respect to the replacing liquid is low, direct replacement of the buffer solution may cause the precipitation of the ionic compound, which may block the flow path. Thus, the purging using a plurality of liquids needs to be performed. In this case, the user needs to appropriately set a purging order and a mixing rate of the plurality of liquids. This requires certain knowledge and attention. As a result, only a skilled user can perform the appropriate setting.
Further, in the usual purge operation, the liquid replacement can be done in the flow path in an outlet of a liquid transfer section and in the flow path up to the in front of an analysis column. However, in the replacement between the liquids which are not miscible with each other and of which properties are completely different from each other, the liquid is not replaced sufficiently by the direct replacement. Therefore, after the replacement is performed with the liquid having an intermediate property of both liquids for all the flow paths, the replacement into a target liquid needs to be made. Thus, in such a case, the usual liquid feeding operation needs to be performed over all the flow paths during the purge operation. Accordingly, the automation of the liquid replacement is difficult to be realized.